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  • NSLinguisticTagger on the contents of an NSTextStorage- crashing bug

    - by Remy Porter
    I'm trying to use an NSLinguisticTagger to monitor the contents of an NSTextStorage and provide some contextual information based on what the user types. To that end, I have an OverlayManager object, which wires up this relationship: -(void) setView:(NSTextView*) view { _view = view; _layout = view.layoutManager; _storage = view.layoutManager.textStorage; //get the TextStorage from the view [_tagger setString:_storage.string]; //pull the string out, this grabs the mutable version [self registerForNotificationsOn:self->_storage]; //subscribe to the willProcessEditing notification } When an edit occurs, I make sure to trap it and notify the tagger (and yes, I know I'm being annoyingly inconsistent with member access, I'm rusty on Obj-C, I'll fix it later): - (void) textStorageWillProcessEditing:(NSNotification*) notification{ if ([self->_storage editedMask] & NSTextStorageEditedCharacters) { NSRange editedRange = [self->_storage editedRange]; NSUInteger delta = [self->_storage changeInLength]; [_tagger stringEditedInRange:editedRange changeInLength:delta]; //should notify the tagger of the changes [self highlightEdits:self]; } } The highlightEdits message delegates the job out to a pool of "Overlay" objects. Each contains a block of code similar to this: [tagger enumerateTagsInRange:range scheme:NSLinguisticTagSchemeLexicalClass options:0 usingBlock:^(NSString *tag, NSRange tokenRange, NSRange sentenceRange, BOOL *stop) { if (tag == PartOfSpeech) { [self applyHighlightToRange:tokenRange onStorage:storage]; } }]; And that's where the problem is- the enumerateTagsInRange method crashes out with a message: 2014-06-04 10:07:19.692 WritersEditor[40191:303] NSMutableRLEArray replaceObjectsInRange:withObject:length:: Out of bounds This problem doesn't occur if I don't link to the mutable copy of the underlying string and instead do a [[_storage string] copy], but obviously I don't want to copy the entire backing store every time I want to do tagging. This all should be happening in the main run loop, so I don't think this is a threading issue. The NSRange I'm enumerating tags on exists both in the NSTextStorage and in the NSLinguisticTagger's view of the string. It's not even the fact that the applyHighlightToRange call adds attributes to the string, because it crashes before even reaching that line. I attempted to build a test case around the problem, but can't replicate it in those situations: - (void) testEdit { NSAttributedString* str = [[NSMutableAttributedString alloc] initWithString:@"Quickly, this is a test."]; text = [[NSTextStorage alloc] initWithAttributedString:str]; NSArray* schemes = [NSLinguisticTagger availableTagSchemesForLanguage:@"en"]; tagger = [[NSLinguisticTagger alloc] initWithTagSchemes:schemes options:0]; [tagger setString:[text string]]; [text beginEditing]; [[text mutableString] appendString:@"T"]; NSRange edited = [text editedRange]; NSUInteger length = [text changeInLength]; [text endEditing]; [tagger stringEditedInRange:edited changeInLength:length]; [tagger enumerateTagsInRange:edited scheme:NSLinguisticTagSchemeLexicalClass options:0 usingBlock:^(NSString *tag, NSRange tokenRange, NSRange sentenceRange, BOOL *stop) { //doesn't matter, this should crash }]; } That code doesn't crash.

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  • How to Sync CI (Hudson) Activity into an existing automated Build Process (phing, svn)?

    - by maraspin
    OUR CURRENT BUILD PROCESS We're a small team of developers (2 to 4 people depending on project) who currently use Phing to deploy code to a staging environment, before going live. We keep our code in a SVN repo, where the trunk holds current active development and, at certain times, we do make branches that we test and then (if successful), tag and export to the staging env. If everything goes well there too, we finally deploy'em in production servers. Actions are highly automated, but always triggered by human intervention. THE DOUBT We'd now like to introduce Continuous Integration (with Hudson) in the process; unfortunately we have a few doubts about activity syncing, since we're afraid that CI could somewhat interfere with our build process and cause certain problems. Considering that an automated CI cycle has a certain frequency of automatically executed actions, we see 2 possible cases for "integration", each with its own problems: Case A: each CI cycle produces a new branch with its own name; we do use such a name to manually (through phing as it happens now) export the code from the SVN to the staging env. The problem I see here is that (unless specific countermeasures are taken - IE deletion) the number of branches we have can easily grow out of control (let's suppose we commit often, so that we have a fresh new build/branch every N minutes). Case B: each CI cycle creates a new branch named 'current', which is then tagged with a unique name only when we manually decide to export it to staging; the current branch, at any case is then deleted, as soon as the next CI cycle starts up. The problem we see here is that a new cycle could kick in while someone is tagging/exporting the 'current' branch to staging thus creating an inconsistent build (but maybe here I'm just too pessimist, since I confess I don't know whether SVN offers some built-in protection against this). With all this being said, I was wondering if anyone with similar experiences could be so kind to give us some hints on the subject, since none of the approaches depicted above looks completely satisfing to us. Is there something important we just completely left off in the overall picture? Thanks for your attention & (in advance) for your help!

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  • When to call glEnable(GL_FRAMEBUFFER_SRGB)?

    - by Steven Lu
    I have a rendering system where I draw to an FBO with a multisampled renderbuffer, then blit it to another FBO with a texture in order to resolve the samples in order to read off the texture to perform post-processing shading while drawing to the backbuffer (FBO index 0). Now I'd like to get some correct sRGB output... The problem is the behavior of the program is rather inconsistent between when I run it on OS X and Windows and this also changes depending on the machine: On Windows with the Intel HD 3000 it will not apply the sRGB nonlinearity but on my other machine with a Nvidia GTX 670 it does. On the Intel HD 3000 in OS X it will also apply it. So this probably means that I'm not setting my GL_FRAMEBUFFER_SRGB enable state at the right points in the program. However I can't seem to find any tutorials that actually tell me when I ought to enable it, they only ever mention that it's dead easy and comes at no performance cost. I am currently not loading in any textures so I haven't had a need to deal with linearizing their colors yet. To force the program to not simply spit back out the linear color values, what I have tried is simply comment out my glDisable(GL_FRAMEBUFFER_SRGB) line, which effectively means this setting is enabled for the entire pipeline, and I actually redundantly force it back on every frame. I don't know if this is correct or not. It certainly does apply a nonlinearization to the colors but I can't tell if this is getting applied twice (which would be bad). It could apply the gamma as I render to my first FBO. It could do it when I blit the first FBO to the second FBO. Why not? I've gone so far as to take screen shots of my final frame and compare raw pixel color values to the colors I set them to in the program: I set the input color to RGB(1,2,3) and the output is RGB(13,22,28). That seems like quite a lot of color compression at the low end and leads me to question if the gamma is getting applied multiple times. I have just now gone through the sRGB equation and I can verify that the conversion seems to be only applied once as linear 1/255, 2/255, and 3/255 do indeed map to sRGB 13/255, 22/255, and 28/255 using the equation 1.055*C^(1/2.4)+0.055. Given that the expansion is so large for these low color values it really should be obvious if the sRGB color transform is getting applied more than once. So, I still haven't determined what the right thing to do is. does glEnable(GL_FRAMEBUFFER_SRGB) only apply to the final framebuffer values, in which case I can just set this during my GL init routine and forget about it hereafter?

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  • Casting between variant and bstr_t causing inconsisten crash in Windows 2008

    - by user58470
    We have a C# application, calling a simple C++ wrapper class, that then calls an existing C++ DLL. The C++ code is all VC++ 6.0. We are getting inconsistent behaviour, but the crash, when it happens, always happens within the C++ wrapper DLL, and always in the same spot (have confirmed using painful logging statements). It never happens on any environment except on Windows 2008, so we suspect some bad-but-not-fatal memory trashing is going on that somehow Windows 2008 is being more mindful of. Here's the relevant code, if anyone has any ideas on why this might be crashing it would be much appreciated. We've been tearing our hair out for a few days and project timelines are slipping all for the want of being able to return a simple string back to C#... I've been told we've tried setting the VARIANT vresult using VariantInit, and clearing it when we are done with VariantClear, but that didn't help. // JobMgrDll.cpp : Defines the entry point for the DLL application. // #include "stdafx.h" #include "JobMgrDll.h" #include "jobmgr.h" CString gcontext; CString guser; CString ghost; CString glog; JOBMGRDLL_API int nJobMgrDll=0; extern "C" JOBMGRDLL_API char* perform_billcalc(char* cmd, char* context, char* user,char* host,BSTR* log,int* loglen) { char* result = new char[1000]; memset(result,0,999); result[999] = '\0'; bstr_t bt_command = cmd; UUID uuid = __uuidof(BRLib::Rules); VARIANT vresult; char *p_rv; gcontext = context; guser = user; ghost = host; write_log("execute_job"); p_rv = execute_job(uuid, "none", bt_command, &vresult); write_log("DONE execute_job"); CString message; write_log ("Intializing bstr_t with variant"); // WE ALWAYS GET HERE bstr_t res(vresult); //message.Format("%s result = %s",p_rv,res); //write_log(message); write_log("copying Result"); // WE DON'T ALWAYS GET HERE, BUT SOMETIMES WE DO strcpy(result,(char*)res); write_log(CString(result)); *loglen = glog.GetLength(); *log = glog.AllocSysString(); return result; } Again, any ideas much, much appreciated.

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  • Thread class closing from other Class (Activity) with protected void onStop() Android

    - by user1761337
    I have a Problem with Closing the Thread. I will Closing the Thread with onStop,onPause and onDestroy. This is my Source in the Activity Class: @Override protected void onStop(){ super.onStop(); finish(); } @Override protected void onPause() { super.onPause(); finish(); } @Override public void onDestroy() { this.mWakeLock.release(); super.onDestroy(); } And the Thread Class: public class GameThread extends Thread { private SurfaceHolder mSurfaceHolder; private Handler mHandler; private Context mContext; private Paint mLinePaint; private Paint blackPaint; //for consistent rendering private long sleepTime; //amount of time to sleep for (in milliseconds) private long delay=1000/30; //state of game (Running or Paused). int state = 1; public final static int RUNNING = 1; public final static int PAUSED = 2; public final static int STOPED = 3; GameSurface gEngine; public GameThread(SurfaceHolder surfaceHolder, Context context, Handler handler,GameSurface gEngineS){ //data about the screen mSurfaceHolder = surfaceHolder; mHandler = handler; mContext = context; gEngine=gEngineS; } //This is the most important part of the code. It is invoked when the call to start() is //made from the SurfaceView class. It loops continuously until the game is finished or //the application is suspended. private long beforeTime; @Override public void run() { //UPDATE while (state==RUNNING) { Log.d("State","Thread is runnig"); //time before update beforeTime = System.nanoTime(); //This is where we update the game engine gEngine.Update(); //DRAW Canvas c = null; try { //lock canvas so nothing else can use it c = mSurfaceHolder.lockCanvas(null); synchronized (mSurfaceHolder) { //clear the screen with the black painter. //reset the canvas c.drawColor(Color.BLACK); //This is where we draw the game engine. gEngine.doDraw(c); } } finally { // do this in a finally so that if an exception is thrown // during the above, we don't leave the Surface in an // inconsistent state if (c != null) { mSurfaceHolder.unlockCanvasAndPost(c); } } this.sleepTime = delay-((System.nanoTime()-beforeTime)/1000000L); try { //actual sleep code if(sleepTime>0){ this.sleep(sleepTime); } } catch (InterruptedException ex) { Logger.getLogger(GameThread.class.getName()).log(Level.SEVERE, null, ex); } while (state==PAUSED){ Log.d("State","Thread is pausing"); try { this.sleep(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }} How i can close the Thread from Activity Class??

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  • Play music on iPhone through computer

    - by Kyle Cronin
    Now that I've had my iPhone for a few months, I'm trying an experiment to see if I can't replace the laptop I carry around with my iPhone + internet connected computer. To this end, I've been trying to find a program that will let me play the music on my iPhone through the hardware and software on the host computer. If I recall correctly this was possible a few years ago with the iPod - Linux software like Rhythmbox and Banshee was able to read the music off an iPod and play it through the speakers. I even thought I recalled iTunes itself being capable of this at one time. Now, however, iTunes greys out/disables the music on my iPhone and I can't find any documented support for the iPhone in any other music program. Is this really no longer possible? Am I limited to using the headphone jack to get music to play? (note: I am using an iPhone 3G with the 3.0 software. I am attempting to play music on computers other than the one I sync with) Several replies mention that I should check "manually manage" to do this. I just tried this on a computer that I don't sync my iPhone to and it asked me to erase and sync, which is obviously something I don't want to do. update: OK, I checked the "Manually manage music and videos" box on a computer that I didn't sync to (now known as "Computer A"), and it told me that I needed to erase & sync to cause the changes to have effect, so I did. At this point I'm guessing that my iPhone thinks that it's syncing with that computer. I copied over a few songs using the autofill feature. At this point, Computer A sees the maybe 10 or so songs I've copied using autofill. I then plug my iPhone into my Macbook ("Computer B") which I've been syncing with. At this point, I'm pretty sure that it still thought that all my synced content was still on my iPhone. The "manually manage music and videos" checkbox isn't checked, so I check it and go through a similar process where iTunes erases the synced content and I copy over a playlist. At this point, there's no trace of the songs that I copied over from Computer A. So I plug my iPhone into Computer A - in the Music section are the handful of songs that I had copied over earlier, greyed out and unplayable. To make sure that this wasn't some sort of caching issue, I plugged my iPhone into my sister's Macbook ("Computer C") and it lists the same few, greyed out songs that I had copied over from Computer A. Plugging into Computer B doesn't reveal these songs at all, only the songs that it copied over (these are playable). A few things: This inconsistent behavior is driving me insane. Why would my iPhone report two versions of its contents to different computers? Is there a way to get a computer to completely forget about an iPhone and just resync everything to get everything into a consistent state? Even if I get the phone into a consistent state, I still can't play the files on my phone anywhere but the computer I sync with, which was my original goal. What am I doing wrong? maybe I should read the fine print before I mess with my iPhone So going over this thread with a fine-toothed comb again yields this lovely tidbit in the Apple docs: Note: Even when manually managing, some content may only be available from one library at time. This includes all content on iPhone and video content on iPods. OK, so manually managing is a dead end on the iPhone. Are there any other options? Any unofficial third-party programs or drivers that will work?

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  • Integrating HP Systems Insight Manager into an existing environment

    - by ewwhite
    I'm working with an environment that spans multiple data centers/sites and consists primarily of HP ProLiant servers (G5-G7) running Linux. The mix is 30% RHEL/CentOS, the rest are Gentoo :(. I also have a few dozen virtual machines running back-office and Windows servers on VMWare ESX hosts. I run OpenNMS to pull SNMP data from the various server nodes and networking devices. While OpenNMS works wonderfully for up/down, thresholds and notifications, it's native handling of traps is a little rough and the graphs are not particularly pretty. I use Orca/RRD graphs for performance trending and nice graphs. I'm tasked with inventorying the environment and wanted to come up with a clean way to organize server information. Since my environment is mostly HP, I've been playing with HP Systems Insight Manager as a way to extract server data and to deploy HP health/monitoring packages and firmware. The Gentoo systems eventually have to be converted to CentOS, so getting a quick assessment of what hardware is where would be great. Although I've read through a few hundred pages of HP manuals, I'm having a difficult time understanding how to get HP SIM to do what I want, though. My main problems are: I have about 40 subnets to deal with; 98% connected with private lines to facilities across the globe. I don't want to initiate an HP SIM discovery only to pull back every piece of intermediate networking hardware and equipment from all of the locations. I'd like this to focus on the servers. I have OpenNMS configured to accept traps. I don't want HP SIM to duplicate that effort. It seems like the built-in software deployment tool wants to overwrite the trapsink parameters for the systems it encounters during discovery. I have about 10 administrative username/password combinations in use across this infrastructure. Is there a more efficient way to get HP SIM to do the discovery or break discovery into manageable chunks? In terms of general workflow, do people typically install the HP Management Agents during the initial OS deployment (e.g. kickstart post script) or afterwards from HP SIM? Is HP SIM too thick/fat to be an inventory tool? I can't tell if it's meant to be used standalone or alongside other monitoring products. Since the majority of the systems I'm trying to track are those running Gentoo (in order to plan the move to CentOS), is there any way for HP SIM to extract system model information from them ( like dmidecode)? I have systems here where I may have an SSH key established, but not direct user or login access. Is there a way for me to import an SSH private/public key pair into HP SIM to reach out to the servers that can't accept standard credentials? There are a handful of sites where I have inconsistent access or have a double-NAT situation. I may be able to poke a server, but it may not be able to find its way back to the management system. Is there a workaround for this? The certificate configuration for HP SIM seems complicated. What is the preferred setup for trust between systems? I'd also appreciate any notes or recommendations to using this product. Or if there's a better way to do this, I'd like to know.

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  • Local DNS server (bind) and the router DHCP

    - by Luca
    I just set up an internal http server for internal use (I set up Redmine), in a small network (30 or so PCs). I set up the http server on a virtual box ubuntu, that runs also the DNS server (bind). In the DNS lookup I added the Redmine server name (redmine.engserver <- 192.168.1.14) and as forwarders the outside ISP DNS IP adresses. I am using a small wi-fi router (ASUS RT-N66U) as DHCP (and as gateway). In the DHCP config page I set up as DNS the ubuntu server IP (it is fixed 192.168.1.14). Now when I connect a new PC to the network, the DHCP router issues its new IP and as DNS servers it issues: primary: 192.168.1.14 (ubuntu machine) and seconary 192.168.1.1 (the router itself). ipconfig /all Default Gateway . . . . . . . . . : 192.168.1.1 DHCP Server . . . . . . . . . . . : 192.168.1.1 DHCPv6 IAID . . . . . . . . . . . : 248539109 DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-17-15-AA-3F-D0-67-E5-49-A7-EF DNS Servers . . . . . . . . . . . : 192.168.1.14 192.168.1.1 NetBIOS over Tcpip. . . . . . . . : Enabled Before changing the DHCP setting on the router, I would always get only one DNS server: 192.168.1.1 (which uses probably DNS forwarding to external public DNS services). The problem is this: If in my browser I type www.google.com, it works all the time. If in the browser I type http://redmine.engserver/ it works most of the time, but sometimes it ends up with a yahoo page search or something else. In the DNS cache it shows as (Server not found). ipconfig /displaydns I looked with wireshark and it seems like sometimes the client PC interrogates the secondary DNS (192.168.1.1) instead of the first 192.168.1.14. Obviously this one is a public domain and it does not have the redmine.engserver entry. What is wrong in this configuration? Is it even legitimate to have 2 DNS (one internal and one forwarded by the router) which are inconsistent? Is there another way to have a local name service in a small office network? Why is the router DHCP issuing itself as DNS?

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  • Distributed and/or Parallel SSIS processing

    - by Jeff
    Background: Our company hosts SaaS DSS applications, where clients provide us data Daily and/or Weekly, which we process & merge into their existing database. During business hours, load in the servers are pretty minimal as it's mostly users running simple pre-defined queries via the website, or running drill-through reports that mostly hit the SSAS OLAP cube. I manage the IT Operations Team, and so far this has presented an interesting "scaling" issue for us. For our daily-refreshed clients, the server is only "busy" for about 4-6 hrs at night. For our weekly-refresh clients, the server is only "busy" for maybe 8-10 hrs per week! We've done our best to use some simple methods of distributing the load by spreading the daily clients evenly among the servers such that we're not trying to process daily clients back-to-back over night. But long-term this scaling strategy creates two notable issues. First, it's going to consume a pretty immense amount of hardware that sits idle for large periods of time. Second, it takes significant Production Support over-head to basically "schedule" the ETL such that they don't over-lap, and move clients/schedules around if they out-grow the resources on a particular server or allocated time-slot. As the title would imply, one option we've tried is running multiple SSIS packages in parallel, but in most cases this has yielded VERY inconsistent results. The most common failures are DTExec, SQL, and SSAS fighting for physical memory and throwing out-of-memory errors, and ETLs running 3,4,5x longer than expected. So from my practical experience thus far, it seems like running multiple ETL packages on the same hardware isn't a good idea, but I can't be the first person that doesn't want to scale multiple ETLs around manual scheduling, and sequential processing. One option we've considered is virtualizing the servers, which obviously doesn't give you any additional resources, but moves the resource contention onto the hypervisor, which (from my experience) seems to manage simultaneous CPU/RAM/Disk I/O a little more gracefully than letting DTExec, SQL, and SSAS battle it out within Windows. Question to the forum: So my question to the forum is, are we missing something obvious here? Are there tools out there that can help manage running multiple SSIS packages on the same hardware? Would it be more "efficient" in terms of parallel execution if instead of running DTExec, SQL, and SSAS same machine (with every machine running that configuration), we run in pairs of three machines with SSIS running on one machine, SQL on another, and SSAS on a third? Obviously that would only make sense if we could process more than the three ETL we were able to process on the machine independently. Another option we've considered is completely re-architecting our SSIS package to have one "master" package for all clients that attempts to intelligently chose a server based off how "busy" it already is in terms of CPU/Memory/Disk utilization, but that would be a herculean effort, and seems like we're trying to reinvent something that you would think someone would sell (although I haven't had any luck finding it). So in summary, are we missing an obvious solution for this, and does anyone know if any tools (for free or for purchase, doesn't matter) that facilitate running multiple SSIS ETL packages in parallel and on multiple servers? (What I would call a "queue & node based" system, but that's not an official term). Ultimately VMWare's Distributed Resource Scheduler addresses this as you simply run a consistent number of clients per VM that you know will never conflict scheduleing-wise, then leave it up to VMWare to move the VMs around to balance out hardware usage. I'm definitely not against using VMWare to do this, but since we're a 100% Microsoft app stack, it seems like -someone- out there would have solved this problem at the application layer instead of the hypervisor layer by checking on resource utilization at the OS, SQL, SSAS levels. I'm open to ANY discussion on this, and remember no suggestion is too crazy or radical! :-) Right now, VMWare is the only option we've found to get away from "manually" balancing our resources, so any suggestions that leave us on a pure Microsoft stack would be great. Thanks guys, Jeff

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  • Using the BAM Interceptor with Continuation

    - by Charles Young
    Originally posted on: http://geekswithblogs.net/cyoung/archive/2014/06/02/using-the-bam-interceptor-with-continuation.aspxI’ve recently been resurrecting some code written several years ago that makes extensive use of the BAM Interceptor provided as part of BizTalk Server’s BAM event observation library.  In doing this, I noticed an issue with continuations.  Essentially, whenever I tried to configure one or more continuations for an activity, the BAM Interceptor failed to complete the activity correctly.   Careful inspection of my code confirmed that I was initializing and invoking the BAM interceptor correctly, so I was mystified.  However, I eventually found the problem.  It is a logical error in the BAM Interceptor code itself. The BAM Interceptor provides a useful mechanism for implementing dynamic tracking.  It supports configurable ‘track points’.  These are grouped into named ‘locations’.  BAM uses the term ‘step’ as a synonym for ‘location’.   Each track point defines a BAM action such as starting an activity, extracting a data item, enabling a continuation, etc.  Each step defines a collection of track points. Understanding Steps The BAM Interceptor provides an abstract model for handling configuration of steps.  It doesn’t, however, define any specific configuration mechanism (e.g., config files, SSO, etc.)  It is up to the developer to decide how to store, manage and retrieve configuration data.  At run time, this configuration is used to register track points which then drive the BAM Interceptor. The full semantics of a step are not immediately clear from Microsoft’s documentation.  They represent a point in a business activity where BAM tracking occurs.  They are named locations in the code.  What is less obvious is that they always represent either the full tracking work for a given activity or a discrete fragment of that work which commences with the start of a new activity or the continuation of an existing activity.  The BAM Interceptor enforces this by throwing an error if no ‘start new’ or ‘continue’ track point is registered for a named location. This constraint implies that each step must marked with an ‘end activity’ track point.  One of the peculiarities of BAM semantics is that when an activity is continued under a correlated ID, you must first mark the current activity as ‘ended’ in order to ensure the right housekeeping is done in the database.  If you re-start an ended activity under the same ID, you will leave the BAM import tables in an inconsistent state.  A step, therefore, always represents an entire unit of work for a given activity or continuation ID.  For activities with continuation, each unit of work is termed a ‘fragment’. Instance and Fragment State Internally, the BAM Interceptor maintains state data at two levels.  First, it represents the overall state of the activity using a ‘trace instance’ token.  This token contains the name and ID of the activity together with a couple of state flags.  The second level of state represents a ‘trace fragment’.   As we have seen, a fragment of an activity corresponds directly to the notion of a ‘step’.  It is the unit of work done at a named location, and it must be bounded by start and end, or continue and end, actions. When handling continuations, the BAM Interceptor differentiates between ‘root’ fragments and other fragments.  Very simply, a root fragment represents the start of an activity.  Other fragments represent continuations.  This is where the logic breaks down.  The BAM Interceptor loses state integrity for root fragments when continuations are defined. Initialization Microsoft’s BAM Interceptor code supports the initialization of BAM Interceptors from track point configuration data.  The process starts by populating an Activity Interceptor Configuration object with an array of track points.  These can belong to different steps (aka ‘locations’) and can be registered in any order.  Once it is populated with track points, the Activity Interceptor Configuration is used to initialise the BAM Interceptor.  The BAM Interceptor sets up a hash table of array lists.  Each step is represented by an array list, and each array list contains an ordered set of track points.  The BAM Interceptor represents track points as ‘executable’ components.  When the OnStep method of the BAM Interceptor is called for a given step, the corresponding list of track points is retrieved and each track point is executed in turn.  Each track point retrieves any required data using a call back mechanism and then serializes a BAM trace fragment object representing a specific action (e.g., start, update, enable continuation, stop, etc.).  The serialised trace fragment is then handed off to a BAM event stream (buffered or direct) which takes the appropriate action. The Root of the Problem The logic breaks down in the Activity Interceptor Configuration.  Each Activity Interceptor Configuration is initialised with an instance of a ‘trace instance’ token.  This provides the basic metadata for the activity as a whole.  It contains the activity name and ID together with state flags indicating if the activity ID is a root (i.e., not a continuation fragment) and if it is completed.  This single token is then shared by all trace actions for all steps registered with the Activity Interceptor Configuration. Each trace instance token is automatically initialised to represent a root fragment.  However, if you subsequently register a ‘continuation’ step with the Activity Interceptor Configuration, the ‘root’ flag is set to false at the point the ‘continue’ track point is registered for that step.   If you use a ‘reflector’ tool to inspect the code for the ActivityInterceptorConfiguration class, you can see the flag being set in one of the overloads of the RegisterContinue method.    This makes no sense.  The trace instance token is shared across all the track points registered with the Activity Interceptor Configuration.  The Activity Interceptor Configuration is designed to hold track points for multiple steps.  The ‘root’ flag is clearly meant to be initialised to ‘true’ for the preliminary root fragment and then subsequently set to false at the point that a continuation step is processed.  Instead, if the Activity Interceptor Configuration contains a continuation step, it is changed to ‘false’ before the root fragment is processed.  This is clearly an error in logic. The problem causes havoc when the BAM Interceptor is used with continuation.  Effectively the root step is no longer processed correctly, and the ultimate effect is that the continued activity never completes!   This has nothing to do with the root and the continuation being in the same process.  It is due to a fundamental mistake of setting the ‘root’ flag to false for a continuation before the root fragment is processed. The Workaround Fortunately, it is easy to work around the bug.  The trick is to ensure that you create a new Activity Interceptor Configuration object for each individual step.  This may mean filtering your configuration data to extract the track points for a single step or grouping the configured track points into individual steps and the creating a separate Activity Interceptor Configuration for each group.  In my case, the first approach was required.  Here is what the amended code looks like: // Because of a logic error in Microsoft's code, a separate ActivityInterceptorConfiguration must be used // for each location. The following code extracts only those track points for a given step name (location). var trackPointGroup = from ResolutionService.TrackPoint tp in bamActivity.TrackPoints                       where (string)tp.Location == bamStepName                       select tp; var bamActivityInterceptorConfig =     new Microsoft.BizTalk.Bam.EventObservation.ActivityInterceptorConfiguration(activityName); foreach (var trackPoint in trackPointGroup) {     switch (trackPoint.Type)     {         case TrackPointType.Start:             bamActivityInterceptorConfig.RegisterStartNew(trackPoint.Location, trackPoint.ExtractionInfo);             break; etc… I’m using LINQ to filter a list of track points for those entries that correspond to a given step and then registering only those track points on a new instance of the ActivityInterceptorConfiguration class.   As soon as I re-wrote the code to do this, activities with continuations started to complete correctly.

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  • Master Data Management and Cloud Computing

    - by david.butler(at)oracle.com
    Cloud Computing is all the rage these days. There are many reasons why this is so. But like its predecessor, Service Oriented Architecture, it can fall on hard times if the underlying data is left unmanaged. Master Data Management is the perfect Cloud companion. It can materially increase the chances for successful Cloud initiatives. In this blog, I'll review the nature of the Cloud and show how MDM fits in.   Here's the National Institute of Standards and Technology Cloud definition: •          Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources that can be rapidly provisioned and released with minimal management effort or service provider interaction.   Cloud architectures have three main layers: applications or Software as a Service (SaaS), Platforms as a Service (PaaS), and Infrastructure as a Service (IaaS). SaaS generally refers to applications that are delivered to end-users over the Internet. Oracle CRM On Demand is an example of a SaaS application. Today there are hundreds of SaaS providers covering a wide variety of applications including Salesforce.com, Workday, and Netsuite. Oracle MDM applications are located in this layer of Oracle's On Demand enterprise Cloud platform. We call it Master Data as a Service (MDaaS). PaaS generally refers to an application deployment platform delivered as a service. They are often built on a grid computing architecture and include database and middleware. Oracle Fusion Middleware is in this category and includes the SOA and Data Integration products used to connect SaaS applications including MDM. Finally, IaaS generally refers to computing hardware (servers, storage and network) delivered as a service.  This typically includes the associated software as well: operating systems, virtualization, clustering, etc.    Cloud Computing benefits are compelling for a large number of organizations. These include significant cost savings, increased flexibility, and fast deployments. Cost advantages include paying for just what you use. This is especially critical for organizations with variable or seasonal usage. Companies don't have to invest to support peak computing periods. Costs are also more predictable and controllable. Increased agility includes access to the latest technology and experts without making significant up front investments.   While Cloud Computing is certainly very alluring with a clear value proposition, it is not without its challenges. An IDC survey of 244 IT executives/CIOs and their line-of-business (LOB) colleagues identified a number of issues:   Security - 74% identified security as an issue involving data privacy and resource access control. Integration - 61% found that it is hard to integrate Cloud Apps with in-house applications. Operational Costs - 50% are worried that On Demand will actually cost more given the impact of poor data quality on the rest of the enterprise. Compliance - 49% felt that compliance with required regulatory, legal and general industry requirements (such as PCI, HIPAA and Sarbanes-Oxley) would be a major issue. When control is lost, the ability of a provider to directly manage how and where data is deployed, used and destroyed is negatively impacted.  There are others, but I singled out these four top issues because Master Data Management, properly incorporated into a Cloud Computing infrastructure, can significantly ameliorate all of these problems. Cloud Computing can literally rain raw data across the enterprise.   According to fellow blogger, Mike Ferguson, "the fracturing of data caused by the adoption of cloud computing raises the importance of MDM in keeping disparate data synchronized."   David Linthicum, CTO Blue Mountain Labs blogs that "the lack of MDM will become more of an issue as cloud computing rises. We're moving from complex federated on-premise systems, to complex federated on-premise and cloud-delivered systems."    Left unmanaged, non-standard, inconsistent, ungoverned data with questionable quality can pollute analytical systems, increase operational costs, and reduce the ROI in Cloud and On-Premise applications. As cloud computing becomes more relevant, and more data, applications, services, and processes are moved out to cloud computing platforms, the need for MDM becomes ever more important. Oracle's MDM suite is designed to deal with all four of the above Cloud issues listed in the IDC survey.   Security - MDM manages all master data attribute privacy and resource access control issues. Integration - MDM pre-integrates Cloud Apps with each other and with On Premise applications at the data level. Operational Costs - MDM significantly reduces operational costs by increasing data quality, thereby improving enterprise business processes efficiency. Compliance - MDM, with its built in Data Governance capabilities, insures that the data is governed according to organizational standards. This facilitates rapid and accurate reporting for compliance purposes. Oracle MDM creates governed high quality master data. A unified cleansed and standardized data view is produced. The Oracle Customer Hub creates a single view of the customer. The Oracle Product Hub creates high quality product data designed to support all go-to-market processes. Oracle Supplier Hub dramatically reduces the chances of 'supplier exceptions'. Oracle Site Hub masters locations. And Oracle Hyperion Data Relationship Management masters financial reference data and manages enterprise hierarchies across operational areas from ERP to EPM and CRM to SCM. Oracle Fusion Middleware connects Cloud and On Premise applications to MDM Hubs and brings high quality master data to your enterprise business processes.   An independent analyst once said "Poor data quality is like dirt on the windshield. You may be able to drive for a long time with slowly degrading vision, but at some point, you either have to stop and clear the windshield or risk everything."  Cloud Computing has the potential to significantly degrade data quality across the enterprise over time. Deploying a Master Data Management solution prior to or in conjunction with a move to the Cloud can insure that the data flowing into the enterprise from the Cloud is clean and governed. This will in turn insure that expected returns on the investment in Cloud Computing will be realized.       Oracle MDM has proven its metal in this area and has the customers to back that up. In fact, I will be hosting a webcast on Tuesday, April 10th at 10 am PT with one of our top Cloud customers, the Church Pension Group. They have moved all mainline applications to a hosted model and use Oracle MDM to insure the master data is managed and cleansed before it is propagated to other cloud and internal systems. I invite you join Martin Hossfeld, VP, IT Operations, and Danette Patterson, Enterprise Data Manager as they review business drivers for MDM and hosted applications, how they did it, the benefits achieved, and lessons learned. You can register for this free webcast here.  Hope to see you there.

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  • ubuntu 12.04 python problem or?

    - by Trki
    Hi i am trying to fix this for a long time but without success. When i open my zsh terminal i get this error: (terminal is working but error appear) Welcome to the world of tomorrow! virtualenvwrapper_run_hook:12: permission denied: virtualenvwrapper.sh: There was a problem running the initialization hooks. If Python could not import the module virtualenvwrapper.hook_loader, check that virtualenv has been installed for VIRTUALENVWRAPPER_PYTHON= and that PATH is set properly. I tried few things but... dont know how to solve it. Somehow during looking for a search i found i should post here an output of: ? sudo dpkg --configure -a Setting up python-pip (1.0-1build1) ... /var/lib/dpkg/info/python-pip.postinst: 6: /var/lib/dpkg/info/python-pip.postinst: pycompile: not found dpkg: error processing python-pip (--configure): subprocess installed post-installation script returned error exit status 127 Setting up libc-dev-bin (2.15-0ubuntu10.5) ... Setting up gnome-control-center-data (1:3.4.2-0ubuntu0.13) ... Setting up linux-libc-dev (3.2.0-56.86) ... Setting up python-virtualenv (1.7.1.2-1) ... /var/lib/dpkg/info/python-virtualenv.postinst: 6: /var/lib/dpkg/info/python-virtualenv.postinst: pycompile: not found dpkg: error processing python-virtualenv (--configure): subprocess installed post-installation script returned error exit status 127 Setting up libglib2.0-0 (2.32.4-0ubuntu1) ... Setting up libglib2.0-0:i386 (2.32.4-0ubuntu1) ... Setting up gimp (2.6.12-1ubuntu1.2) ... /var/lib/dpkg/info/gimp.postinst: 11: /var/lib/dpkg/info/gimp.postinst: pycompile: not found dpkg: error processing gimp (--configure): subprocess installed post-installation script returned error exit status 127 Setting up libpolkit-gobject-1-0 (0.104-1ubuntu1.1) ... Setting up libgnome-control-center1 (1:3.4.2-0ubuntu0.13) ... Setting up libnm-util2 (0.9.4.0-0ubuntu4.3) ... Setting up libc6-dev (2.15-0ubuntu10.5) ... Setting up libpulse-mainloop-glib0 (1:1.1-0ubuntu15.4) ... dpkg: dependency problems prevent configuration of virtualenvwrapper: virtualenvwrapper depends on python-virtualenv; however: Package python-virtualenv is not configured yet. dpkg: error processing virtualenvwrapper (--configure): dependency problems - leaving unconfigured Setting up libpolkit-agent-1-0 (0.104-1ubuntu1.1) ... Setting up libupower-glib1 (0.9.15-3git1ubuntu0.1) ... Setting up libaccountsservice0 (0.6.15-2ubuntu9.6.1) ... Setting up libpolkit-backend-1-0 (0.104-1ubuntu1.1) ... Setting up libglib2.0-bin (2.32.4-0ubuntu1) ... Setting up libnm-glib4 (0.9.4.0-0ubuntu4.3) ... Setting up policykit-1 (0.104-1ubuntu1.1) ... Setting up gnome-settings-daemon (3.4.2-0ubuntu0.6.4) ... Setting up accountsservice (0.6.15-2ubuntu9.6.1) ... dpkg: error processing ubuntu-system-service (--configure): Package is in a very bad inconsistent state - you should reinstall it before attempting configuration. Processing triggers for libc-bin ... ldconfig deferred processing now taking place Errors were encountered while processing: python-pip python-virtualenv gimp virtualenvwrapper ubuntu-system-service Also: ? python --version zsh: command not found: python Part of my ~/.zshrc # python virtual env wrapper if [ -f ~/.local/bin/virtualenvwrapper.sh ]; then export WORKON_HOME=~/.virtualenvs source ~/.local/bin/virtualenvwrapper.sh plugins=("${plugins[@]}" virtualenvwrapper) fi # pythonbrew [[ -s ~/.pythonbrew/etc/bashrc ]] && source ~/.pythonbrew/etc/bashrc Part os zsh -xv # # Invoke the initialization functions # virtualenvwrapper_initialize +/home/trki/.local/bin/virtualenvwrapper.sh:1179> virtualenvwrapper_initialize +virtualenvwrapper_initialize:1> virtualenvwrapper_derive_workon_home +virtualenvwrapper_derive_workon_home:1> typeset 'workon_home_dir=/home/trki/.virtualenvs' +virtualenvwrapper_derive_workon_home:5> [ /home/trki/.virtualenvs '=' '' ']' +virtualenvwrapper_derive_workon_home:12> echo /home/trki/.virtualenvs +virtualenvwrapper_derive_workon_home:12> unset GREP_OPTIONS +virtualenvwrapper_derive_workon_home:12> grep '^[^/~]' +virtualenvwrapper_derive_workon_home:21> echo /home/trki/.virtualenvs +virtualenvwrapper_derive_workon_home:21> unset GREP_OPTIONS +virtualenvwrapper_derive_workon_home:21> egrep '([\$~]|//)' +virtualenvwrapper_derive_workon_home:30> echo /home/trki/.virtualenvs +virtualenvwrapper_derive_workon_home:31> return 0 +virtualenvwrapper_initialize:1> export 'WORKON_HOME=/home/trki/.virtualenvs' +virtualenvwrapper_initialize:3> virtualenvwrapper_verify_workon_home -q +virtualenvwrapper_verify_workon_home:1> RC=0 +virtualenvwrapper_verify_workon_home:2> [ ! -d /home/trki/.virtualenvs/ ']' +virtualenvwrapper_verify_workon_home:11> return 0 +virtualenvwrapper_initialize:6> [ /home/trki/.virtualenvs '=' '' ']' +virtualenvwrapper_initialize:11> virtualenvwrapper_run_hook initialize +virtualenvwrapper_run_hook:1> typeset hook_script +virtualenvwrapper_run_hook:2> typeset result +virtualenvwrapper_run_hook:4> hook_script=+virtualenvwrapper_run_hook:4> virtualenvwrapper_tempfile initialize-hook +virtualenvwrapper_tempfile:2> typeset 'suffix=initialize-hook' +virtualenvwrapper_tempfile:3> typeset file +virtualenvwrapper_tempfile:5> file=+virtualenvwrapper_tempfile:5> virtualenvwrapper_mktemp -t virtualenvwrapper-initialize-hook-XXXXXXXXXX +virtualenvwrapper_mktemp:1> mktemp -t virtualenvwrapper-initialize-hook-XXXXXXXXXX +virtualenvwrapper_tempfile:5> file=/tmp/virtualenvwrapper-initialize-hook-OhY86PXmo7 +virtualenvwrapper_tempfile:6> [ 0 -ne 0 ']' +virtualenvwrapper_tempfile:6> [ -z /tmp/virtualenvwrapper-initialize-hook-OhY86PXmo7 ']' +virtualenvwrapper_tempfile:6> [ ! -f /tmp/virtualenvwrapper-initialize-hook-OhY86PXmo7 ']' +virtualenvwrapper_tempfile:11> echo /tmp/virtualenvwrapper-initialize-hook-OhY86PXmo7 +virtualenvwrapper_tempfile:12> return 0 +virtualenvwrapper_run_hook:4> hook_script=/tmp/virtualenvwrapper-initialize-hook-OhY86PXmo7 +virtualenvwrapper_run_hook:11> cd /home/trki/.virtualenvs +cd:1> [[ x/home/trki/.virtualenvs == x... ]] +cd:3> [[ x/home/trki/.virtualenvs == x.... ]] +cd:5> [[ x/home/trki/.virtualenvs == x..... ]] +cd:7> [[ x/home/trki/.virtualenvs == x...... ]] +cd:9> [ -d /home/trki/.autoenv ']' +cd:13> cd /home/trki/.virtualenvs +virtualenvwrapper_run_hook:12> '' -m virtualenvwrapper.hook_loader --script /tmp/virtualenvwrapper-initialize-hook-OhY86PXmo7 initialize virtualenvwrapper_run_hook:12: permission denied: +virtualenvwrapper_run_hook:15> result=126 +virtualenvwrapper_run_hook:17> [ 126 -eq 0 ']' +virtualenvwrapper_run_hook:27> [ initialize '=' initialize ']' +virtualenvwrapper_run_hook:29> cat - virtualenvwrapper.sh: There was a problem running the initialization hooks. If Python could not import the module virtualenvwrapper.hook_loader, check that virtualenv has been installed for VIRTUALENVWRAPPER_PYTHON= and that PATH is set properly. +virtualenvwrapper_run_hook:38> rm -f /tmp/virtualenvwrapper-initialize-hook-OhY86PXmo7 +virtualenvwrapper_run_hook:39> return 126 +virtualenvwrapper_initialize:13> virtualenvwrapper_setup_tab_completion +virtualenvwrapper_setup_tab_completion:1> [ -n '' ']' +virtualenvwrapper_setup_tab_completion:20> [ -n 4.3.17 ']' +virtualenvwrapper_setup_tab_completion:30> compctl -K _virtualenvs workon rmvirtualenv cpvirtualenv showvirtualenv +virtualenvwrapper_setup_tab_completion:31> compctl -K _cdvirtualenv_complete cdvirtualenv +virtualenvwrapper_setup_tab_completion:32> compctl -K _cdsitepackages_complete cdsitepackages +virtualenvwrapper_initialize:15> return 0 +/home/trki/.zshrc:17> plugins=( git python django symfony2 zsh-syntax-highlighting composer history-substring-search virtualenvwrapper ) # pythonbrew [[ -s ~/.pythonbrew/etc/bashrc ]] && source ~/.pythonbrew/etc/bashrc +/home/trki/.zshrc:21> [[ -s /home/trki/.pythonbrew/etc/bashrc ]] Also when i try to open ubuntu software center absolutly nothing happens. No idea what to do now.

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  • Oracle's Global Single Schema

    - by david.butler(at)oracle.com
    Maximizing business process efficiencies in a heterogeneous environment is very difficult. The difficulty stems from the fact that the various applications across the Information Technology (IT) landscape employ different integration standards, different message passing strategies, and different workflow engines. Vendors such as Oracle and others are delivering tools to help IT organizations manage the complexities introduced by these differences. But the one remaining intractable problem impacting efficient operations is the fact that these applications have different definitions for the same business data. Business data is your business information codified for computer programs to use. A good data model will represent the way your organization does business. The computer applications your organization deploys to improve operational efficiency are built to operate on the business data organized into this schema.  If the schema does not represent how you do business, the applications on that schema cannot provide the features you need to achieve the desired efficiencies. Business processes span these applications. Data problems break these processes rendering them far less efficient than they need to be to achieve organization goals. Thus, the expected return on the investment in these applications is never realized. The success of all business processes depends on the availability of accurate master data.  Clearly, the solution to this problem is to consolidate all the master data an organization uses to run its business. Then clean it up, augment it, govern it, and connect it back to the applications that need it. Until now, this obvious solution has been difficult to achieve because no one had defined a data model sufficiently broad, deep and flexible enough to support transaction processing on all key business entities and serve as a master superset to all other operational data models deployed in heterogeneous IT environments. Today, the situation has changed. Oracle has created an operational data model (aka schema) that can support accurate and consistent master data across heterogeneous IT systems. This is foundational for providing a way to consolidate and integrate master data without having to replace investments in existing applications. This Global Single Schema (GSS) represents a revolutionary breakthrough that allows for true master data consolidation. Oracle has deep knowledge of applications dating back to the early 1990s.  It developed applications in the areas of Supply Chain Management (SCM), Product Lifecycle Management (PLM), Enterprise Resource Planning (ERP), Customer Relationship Management (CRM), Human Capital Management (HCM), Financials and Manufacturing. In addition, Oracle applications were delivered for key industries such as Communications, Financial Services, Retail, Public Sector, High Tech Manufacturing (HTM) and more. Expertise in all these areas drove requirements for GSS. The following figure illustrates Oracle's unique position that enabled the creation of the Global Single Schema. GSS Requirements Gathering GSS defines all the key business entities and attributes including Customers, Contacts, Suppliers, Accounts, Products, Services, Materials, Employees, Installed Base, Sites, Assets, and Inventory to name just a few. In addition, Oracle delivers GSS pre-integrated with a wide variety of operational applications.  Business Process Automation EBusiness is about maximizing operational efficiency. At the highest level, these 'operations' span all that you do as an organization.  The following figure illustrates some of these high-level business processes. Enterprise Business Processes Supplies are procured. Assets are maintained. Materials are stored. Inventory is accumulated. Products and Services are engineered, produced and sold. Customers are serviced. And across this entire spectrum, Employees do the procuring, supporting, engineering, producing, selling and servicing. Not shown, but not to be overlooked, are the accounting and the financial processes associated with all this procuring, manufacturing, and selling activity. Supporting all these applications is the master data. When this data is fragmented and inconsistent, the business processes fail and inefficiencies multiply. But imagine having all the data under these operational business processes in one place. ·            The same accurate and timely customer data will be provided to all your operational applications from the call center to the point of sale. ·            The same accurate and timely supplier data will be provided to all your operational applications from supply chain planning to procurement. ·            The same accurate and timely product information will be available to all your operational applications from demand chain planning to marketing. You would have a single version of the truth about your assets, financial information, customers, suppliers, employees, products and services to support your business automation processes as they flow across your business applications. All company and partner personnel will access the same exact data entity across all your channels and across all your lines of business. Oracle's Global Single Schema enables this vision of a single version of the truth across the heterogeneous operational applications supporting the entire enterprise. Global Single Schema Oracle's Global Single Schema organizes hundreds of thousands of attributes into 165 major schema objects supporting over 180 business application modules. It is designed for international operations, and extensibility.  The schema is delivered with a full set of public Application Programming Interfaces (APIs) and an Integration Repository with modern Service Oriented Architecture interfaces to make data available as a services (DaaS) to business processes and enable operations in heterogeneous IT environments. ·         Key tables can be extended with unlimited numbers of additional attributes and attribute groups for maximum flexibility.  o    This enables model extensions that reflect business entities unique to your organization's operations. ·         The schema is multi-organization enabled so data manipulation can be controlled along organizational boundaries. ·         It uses variable byte Unicode to support over 31 languages. ·         The schema encodes flexible date and flexible address formats for easy localizations. No matter how complex your business is, Oracle's Global Single Schema can hold your business objects and support your global operations. Oracle's Global Single Schema identifies and defines the business objects an enterprise needs within the context of its business operations. The interrelationships between the business objects are also contained within the GSS data model. Their presence expresses fundamental business rules for the interaction between business entities. The following figure illustrates some of these connections.   Interconnected Business Entities Interconnecte business processes require interconnected business data. No other MDM vendor has this capability. Everyone else has either one entity they can master or separate disconnected models for various business entities. Higher level integrations are made available, but that is a weak architectural alternative to data level integration in this critically important aspect of Master Data Management.    

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  • CLR Version issues with CorBindRuntimeEx

    - by Rick Strahl
    I’m working on an older FoxPro application that’s using .NET Interop and this app loads its own copy of the .NET runtime through some of our own tools (wwDotNetBridge). This all works fine and it’s fairly straightforward to load and host the runtime and then make calls against it. I’m writing this up for myself mostly because I’ve been bitten by these issues repeatedly and spend 15 minutes each However, things get tricky when calling specific versions of the .NET runtime since .NET 4.0 has shipped. Basically we need to be able to support both .NET 2.0 and 4.0 and we’re currently doing it with the same assembly – a .NET 2.0 assembly that is the AppDomain entry point. This works as .NET 4.0 can easily host .NET 2.0 assemblies and the functionality in the 2.0 assembly provides all the features we need to call .NET 4.0 assemblies via Reflection. In wwDotnetBridge we provide a load flag that allows specification of the runtime version to use. Something like this: do wwDotNetBridge LOCAL loBridge as wwDotNetBridge loBridge = CreateObject("wwDotNetBridge","v4.0.30319") and this works just fine in most cases.  If I specify V4 internally that gets fixed up to a whole version number like “v4.0.30319” which is then actually used to host the .NET runtime. Specifically the ClrVersion setting is handled in this Win32 DLL code that handles loading the runtime for me: /// Starts up the CLR and creates a Default AppDomain DWORD WINAPI ClrLoad(char *ErrorMessage, DWORD *dwErrorSize) { if (spDefAppDomain) return 1; //Retrieve a pointer to the ICorRuntimeHost interface HRESULT hr = CorBindToRuntimeEx( ClrVersion, //Retrieve latest version by default L"wks", //Request a WorkStation build of the CLR STARTUP_LOADER_OPTIMIZATION_MULTI_DOMAIN | STARTUP_CONCURRENT_GC, CLSID_CorRuntimeHost, IID_ICorRuntimeHost, (void**)&spRuntimeHost ); if (FAILED(hr)) { *dwErrorSize = SetError(hr,ErrorMessage); return hr; } //Start the CLR hr = spRuntimeHost->Start(); if (FAILED(hr)) return hr; CComPtr<IUnknown> pUnk; WCHAR domainId[50]; swprintf(domainId,L"%s_%i",L"wwDotNetBridge",GetTickCount()); hr = spRuntimeHost->CreateDomain(domainId,NULL,&pUnk); hr = pUnk->QueryInterface(&spDefAppDomain.p); if (FAILED(hr)) return hr; return 1; } CorBindToRuntimeEx allows for a specific .NET version string to be supplied which is what I’m doing via an API call from the FoxPro code. The behavior of CorBindToRuntimeEx is a bit finicky however. The documentation states that NULL should load the latest version of the .NET runtime available on the machine – but it actually doesn’t. As far as I can see – regardless of runtime overrides even in the .config file – NULL will always load .NET 2.0 even if 4.0 is installed. <supportedRuntime> .config File Settings Things get even more unpredictable once you start adding runtime overrides into the application’s .config file. In my scenario working inside of Visual FoxPro this would be VFP9.exe.config in the FoxPro installation folder (not the current folder). If I have a specific runtime override in the .config file like this: <?xml version="1.0"?> <configuration> <startup> <supportedRuntime version="v2.0.50727" /> </startup> </configuration> Not surprisingly with this I can load a .NET 2.0  runtime, but I will not be able to load Version 4.0 of the .NET runtime even if I explicitly specify it in my call to ClrLoad. Worse I don’t get an error – it will just go ahead and hand me a V2 version of the runtime and assume that’s what I wanted. Yuck! However, if I set the supported runtime to V4 in the .config file: <?xml version="1.0"?> <configuration> <startup> <supportedRuntime version="v4.0.30319" /> </startup> </configuration> Then I can load both V4 and V2 of the runtime. Specifying NULL however will STILL only give me V2 of the runtime. Again this seems pretty inconsistent. If you’re hosting runtimes make sure you check which version of the runtime is actually loading first to ensure you get the one you’re looking for. If the wrong version loads – say 2.0 and you want 4.0 - and you then proceed to load 4.0 assemblies they will all fail to load due to version mismatches. This is how all of this started – I had a bunch of assemblies that weren’t loading and it took a while to figure out that the host was running the wrong version of the CLR and therefore caused the assemblies loading to fail. Arrggh! <supportedRuntime> and Debugger Version <supportedRuntime> also affects the use of the .NET debugger when attached to the target application. Whichever runtime is specified in the key is the version of the debugger that fires up. This can have some interesting side effects. If you load a .NET 2.0 assembly but <supportedRuntime> points at V4.0 (or vice versa) the debugger will never fire because it can only debug in the appropriate runtime version. This has bitten me on several occasions where code runs just fine but the debugger will just breeze by breakpoints without notice. The default version for the debugger is the latest version installed on the system if <supportedRuntime> is not set. Summary Besides all the hassels, I’m thankful I can build a .NET 2.0 assembly and have it host .NET 4.0 and call .NET 4.0 code. This way we’re able to ship a single assembly that provides functionality that supports both .NET 2 and 4 without having to have separate DLLs for both which would be a deployment and update nightmare. The MSDN documentation does point at newer hosting API’s specifically for .NET 4.0 which are way more complicated and even less documented but that doesn’t help here because the runtime needs to be able to host both .NET 4.0 and 2.0. Not pleased about that – the new APIs look way more complex and of course they’re not available with older versions of the runtime installed which in our case makes them useless to me in this scenario where I have to support .NET 2.0 hosting (to provide greater ‘built-in’ platform support). Once you know the behavior above, it’s manageable. However, it’s quite easy to get tripped up here because there are multiple combinations that can really screw up behaviors.© Rick Strahl, West Wind Technologies, 2005-2011Posted in .NET  FoxPro  

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  • DRY and SRP

    - by Timothy Klenke
    Originally posted on: http://geekswithblogs.net/TimothyK/archive/2014/06/11/dry-and-srp.aspxKent Beck’s XP Simplicity Rules (aka Four Rules of Simple Design) are a prioritized list of rules that when applied to your code generally yield a great design.  As you’ll see from the above link the list has slightly evolved over time.  I find today they are usually listed as: All Tests Pass Don’t Repeat Yourself (DRY) Express Intent Minimalistic These are prioritized.  If your code doesn’t work (rule 1) then everything else is forfeit.  Go back to rule one and get the code working before worrying about anything else. Over the years the community have debated whether the priority of rules 2 and 3 should be reversed.  Some say a little duplication in the code is OK as long as it helps express intent.  I’ve debated it myself.  This recent post got me thinking about this again, hence this post.   I don’t think it is fair to compare “Expressing Intent” against “DRY”.  This is a comparison of apples to oranges.  “Expressing Intent” is a principal of code quality.  “Repeating Yourself” is a code smell.  A code smell is merely an indicator that there might be something wrong with the code.  It takes further investigation to determine if a violation of an underlying principal of code quality has actually occurred. For example “using nouns for method names”, “using verbs for property names”, or “using Booleans for parameters” are all code smells that indicate that code probably isn’t doing a good job at expressing intent.  They are usually very good indicators.  But what principle is the code smell of Duplication pointing to and how good of an indicator is it? Duplication in the code base is bad for a couple reasons.  If you need to make a change and that needs to be made in a number of locations it is difficult to know if you have caught all of them.  This can lead to bugs if/when one of those locations is overlooked.  By refactoring the code to remove all duplication there will be left with only one place to change, thereby eliminating this problem. With most projects the code becomes the single source of truth for a project.  If a production code base is inconsistent with a five year old requirements or design document the production code that people are currently living with is usually declared as the current reality (or truth).  Requirement or design documents at this age in a project life cycle are usually of little value. Although comparing production code to external documentation is usually straight forward, duplication within the code base muddles this declaration of truth.  When code is duplicated small discrepancies will creep in between the two copies over time.  The question then becomes which copy is correct?  As different factions debate how the software should work, trust in the software and the team behind it erodes. The code smell of Duplication points to a violation of the “Single Source of Truth” principle.  Let me define that as: A stakeholder’s requirement for a software change should never cause more than one class to change. Violation of the Single Source of Truth principle will always result in duplication in the code.  However, the inverse is not always true.  Duplication in the code does not necessarily indicate that there is a violation of the Single Source of Truth principle. To illustrate this, let’s look at a retail system where the system will (1) send a transaction to a bank and (2) print a receipt for the customer.  Although these are two separate features of the system, they are closely related.  The reason for printing the receipt is usually to provide an audit trail back to the bank transaction.  Both features use the same data:  amount charged, account number, transaction date, customer name, retail store name, and etcetera.  Because both features use much of the same data, there is likely to be a lot of duplication between them.  This duplication can be removed by making both features use the same data access layer. Then start coming the divergent requirements.  The receipt stakeholder wants a change so that the account number has the last few digits masked out to protect the customer’s privacy.  That can be solve with a small IF statement whilst still eliminating all duplication in the system.  Then the bank wants to take a picture of the customer as well as capture their signature and/or PIN number for enhanced security.  Then the receipt owner wants to pull data from a completely different system to report the customer’s loyalty program point total. After a while you realize that the two stakeholders have somewhat similar, but ultimately different responsibilities.  They have their own reasons for pulling the data access layer in different directions.  Then it dawns on you, the Single Responsibility Principle: There should never be more than one reason for a class to change. In this example we have two stakeholders giving two separate reasons for the data access class to change.  It is clear violation of the Single Responsibility Principle.  That’s a problem because it can often lead the project owner pitting the two stakeholders against each other in a vein attempt to get them to work out a mutual single source of truth.  But that doesn’t exist.  There are two completely valid truths that the developers need to support.  How is this to be supported and honour the Single Responsibility Principle?  The solution is to duplicate the data access layer and let each stakeholder control their own copy. The Single Source of Truth and Single Responsibility Principles are very closely related.  SST tells you when to remove duplication; SRP tells you when to introduce it.  They may seem to be fighting each other, but really they are not.  The key is to clearly identify the different responsibilities (or sources of truth) over a system.  Sometimes there is a single person with that responsibility, other times there are many.  This can be especially difficult if the same person has dual responsibilities.  They might not even realize they are wearing multiple hats. In my opinion Single Source of Truth should be listed as the second rule of simple design with Express Intent at number three.  Investigation of the DRY code smell should yield to the proper application SST, without violating SRP.  When necessary leave duplication in the system and let the class names express the different people that are responsible for controlling them.  Knowing all the people with responsibilities over a system is the higher priority because you’ll need to know this before you can express it.  Although it may be a code smell when there is duplication in the code, it does not necessarily mean that the coder has chosen to be expressive over DRY or that the code is bad.

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  • Learnings from trying to write better software: Loud errors from the very start

    - by theo.spears
    Microsoft made a very small number of backwards incompatible changes between .NET 1.1 and 2.0, because they wanted to make it as easy and safe as possible to port applications to the new runtime. (Here’s a list.) However, one thing they did change was what happens when a background thread fails with an unhanded exception - in .NET 1.1 nothing happened, the thread terminated, and the application continued oblivious. Try the same trick in .NET 2.0 and the entire application, including all threads, will rudely terminate. There are three reasons for this. Firstly if a background thread has crashed, it may have left the entire application in an inconsistent state, in a way that will affect other threads. It’s better to terminate the entire application than continue and have the application perform actions based on a broken state, for example take customer orders, or write corrupt files to disk.  Secondly, during software development, it is far better for errors to be loud and obtrusive. Even if you have unit tests and integration tests (and you should), a key part of ensuring software works properly is to actually try using it, both through systematic testing and through the casual use all software gets by its developers during use. Subtle errors are easy to miss if you are not actually doing real work using the application, loud errors are obvious. Thirdly, and most importantly, even if catching and swallowing exceptions indiscriminately doesn't cause any problems in your application, the presence of unexpected exceptions shows you do not fully understand the behavior of your code. The currently released version of your application may be absolutely correct. However, because your mental model of the behavior is wrong, any future change you make to the program could and probably will introduce critical errors.  This applies to more than just exceptions causing threads to exit, any unexpected state should make the application blow up in an un-ignorable way. The worst thing you can do is silently swallow errors and continue. And let's be clear, writing to a log file does not count as blowing up in an un-ignorable way.  This is all simple as long as the call stack only contains your code, but when your functions start to be called by third party or .NET framework code, it's surprisingly easy for exceptions to start vanishing. Let's look at two examples.   1. Windows forms drag drop events  Usually if you throw an exception from a winforms event handler it will bring up the "application has crashed" dialog with abort and continue options. This is a good default behavior - the error is big and loud, but it is possible for the user to ignore the error and hopefully save their data, if somehow this bug makes it past testing. However drag and drop are different - throw an exception from one of these and it will just be silently swallowed with no explanation.  By the way, it's not just drag and drop events. Timer events do it too.  You can research how exceptions are treated in different handlers and code appropriately, but the safest and most user friendly approach is to always catch exceptions in your event handlers and show your own error message. I'll talk about one good approach to handling these exceptions at the end of this post.   2. SSMS integration for SQL Tab Magic  A while back wrote an SSMS add-in called SQL Tab Magic (learn more about the process here). It works by listening to certain SSMS events and remembering what documents are opened and closed. I deployed it internally and it was used for a few months by a number of people without problems, so I was reasonably confident in its quality. Before releasing I made a few cleanups, including introducing error reporting. Bam. A few days later I was looking at over 1,000 error reports in my inbox. In turns out I wasn't handling table designers properly. The exceptions were there, but again SSMS was helpfully swallowing them all for me, so I was blissfully unaware. Had I made my errors loud from the start, I would have noticed these issues long before and fixed them.   Handling exceptions  Now you are systematically catching exceptions throughout your application, you need to do something with them. I've tried 3 options: log them, alert the user, and automatically send them home.  There are a few good options for logging in .NET. The most widespread is Apache log4net, which provides a very capable and configurable logging framework. There is also NLog which has a compatible interface, with a greater emphasis on fluent rather than XML configuration.  Alerting the user serves two purposes. Firstly it means they understand their action has failed to they don't just assume it worked (Silent file copy failure is a problem if you then delete the originals) or that they should keep waiting for a background task to complete. Secondly, it means the users can report the bug to your support team, and then you can fix it. This means the message you show the user should contain the information you need as a developer to identify and fix it. And the user will probably just send you a screenshot of the dialog, so it shouldn't be hidden by scroll bars.  This leads us to the third option, automatically sending error reports home. By automatic I mean with minimal effort on the part of the user, rather than doing it silently behind their backs. The advantage of this is you can send back far more detailed and precise information than you can expect a user to include in an email, and by making it easier to report errors, you make it more likely users will do so.  We do this using a great tool called SmartAssembly (full disclosure: this is a product made by Red Gate). It captures complete stack traces including the values of all local variables and then allows the user to send all this information back with a single click. We also capture log files to help understand what lead up to the error. We then use the free SmartAssembly Sync for Jira to dedupe these reports and raise them as bugs in our bug tracking system.  The combined effect of loud errors during development and then automatic error reporting once software is deployed allows us to find and fix more bugs, correct misunderstandings on how our software works, and overall is a key piece in delivering higher quality software. However it is no substitute for having motivated cunning testers in the building - and we're looking to hire more of those too.   If you found this post interesting you should follow me on twitter.  

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  • Five Key Strategies in Master Data Management

    - by david.butler(at)oracle.com
    Here is a very interesting Profit Magazine article on MDM: A recent customer survey reveals the deleterious effects of data fragmentation. by Trevor Naidoo, December 2010   Across industries and geographies, IT organizations have grown in complexity, whether due to mergers and acquisitions, or decentralized systems supporting functional or departmental requirements. With systems architected over time to support unique, one-off process needs, they are becoming costly to maintain, and the Internet has only further added to the complexity. Data fragmentation has become a key inhibitor in delivering flexible, user-friendly systems. The Oracle Insight team conducted a survey assessing customers' master data management (MDM) capabilities over the past two years to get a sense of where they are in terms of their capabilities. The responses, by 27 respondents from six different industries, reveal five key areas in which customers need to improve their data management in order to get better financial results. 1. Less than 15 percent of organizations surveyed understand the sources and quality of their master data, and have a roadmap to address missing data domains. Examples of the types of master data domains referred to are customer, supplier, product, financial and site. Many organizations have multiple sources of master data with varying degrees of data quality in each source -- customer data stored in the customer relationship management system is inconsistent with customer data stored in the order management system. Imagine not knowing how many places you stored your customer information, and whether a customer's address was the most up to date in each source. In fact, more than 55 percent of the respondents in the survey manage their data quality on an ad-hoc basis. It is important for organizations to document their inventory of data sources and then profile these data sources to ensure that there is a consistent definition of key data entities throughout the organization. Some questions to ask are: How do we define a customer? What is a product? How do we define a site? The goal is to strive for one common repository for master data that acts as a cross reference for all other sources and ensures consistent, high-quality master data throughout the organization. 2. Only 18 percent of respondents have an enterprise data management strategy to ensure that data is treated as an asset to the organization. Most respondents handle data at the department or functional level and do not have an enterprise view of their master data. The sales department may track all their interactions with customers as they move through the sales cycle, the service department is tracking their interactions with the same customers independently, and the finance department also has a different perspective on the same customer. The salesperson may not be aware that the customer she is trying to sell to is experiencing issues with existing products purchased, or that the customer is behind on previous invoices. The lack of a data strategy makes it difficult for business users to turn data into information via reports. Without the key building blocks in place, it is difficult to create key linkages between customer, product, site, supplier and financial data. These linkages make it possible to understand patterns. A well-defined data management strategy is aligned to the business strategy and helps create the governance needed to ensure that data stewardship is in place and data integrity is intact. 3. Almost 60 percent of respondents have no strategy to integrate data across operational applications. Many respondents have several disparate sources of data with no strategy to keep them in sync with each other. Even though there is no clear strategy to integrate the data (see #2 above), the data needs to be synced and cross-referenced to keep the business processes running. About 55 percent of respondents said they perform this integration on an ad hoc basis, and in many cases, it is done manually with the help of Microsoft Excel spreadsheets. For example, a salesperson needs a report on global sales for a specific product, but the product has different product numbers in different countries. Typically, an analyst will pull all the data into Excel, manually create a cross reference for that product, and then aggregate the sales. The exact same procedure has to be followed if the same report is needed the following month. A well-defined consolidation strategy will ensure that a central cross-reference is maintained with updates in any one application being propagated to all the other systems, so that data is synchronized and up to date. This can be done in real time or in batch mode using integration technology. 4. Approximately 50 percent of respondents spend manual efforts cleansing and normalizing data. Information stored in various systems usually follows different standards and formats, making it difficult to match the data. A customer's address can be stored in different ways using a variety of abbreviations -- for example, "av" or "ave" for avenue. Similarly, a product's attributes can be stored in a number of different ways; for example, a size attribute can be stored in inches and can also be entered as "'' ". These types of variations make it difficult to match up data from different sources. Today, most customers rely on manual, heroic efforts to match, cleanse, and de-duplicate data -- clearly not a scalable, sustainable model. To solve this challenge, organizations need the ability to standardize data for customers, products, sites, suppliers and financial accounts; however, less than 10 percent of respondents have technology in place to automatically resolve duplicates. It is no wonder, therefore, that we get communications about products we don't own, at addresses we don't reside, and using channels (like direct mail) we don't like. An all-too-common example of a potential challenge follows: Customers end up receiving duplicate communications, which not only impacts customer satisfaction, but also incurs additional mailing costs. Cleansing, normalizing, and standardizing data will help address most of these issues. 5. Only 10 percent of respondents have the ability to share data that was mastered in a master data hub. Close to 60 percent of respondents have efforts in place that profile, standardize and cleanse data manually, and the output of these efforts are stored in spreadsheets in various parts of the organization. This valuable information is not easily shared with the rest of the organization and, more importantly, this enriched information cannot be sent back to the source systems so that the data is fixed at the source. A key benefit of a master data management strategy is not only to clean the data, but to also share the data back to the source systems as well as other systems that need the information. Aside from the source systems, another key beneficiary of this data is the business intelligence system. Having clean master data as input to business intelligence systems provides more accurate and enhanced reporting.  Characteristics of Stellar MDM When deciding on the right master data management technology, organizations should look for solutions that have four main characteristics: enterprise-grade MDM performance complete technology that can be rapidly deployed and addresses multiple business issues end-to-end MDM process management with data quality monitoring and assurance pre-built MDM business relevant applications with data stores and workflows These master data management capabilities will aid in moving closer to a best-practice maturity level, delivering tremendous efficiencies and savings as well as revenue growth opportunities as a result of better understanding your customers.  Trevor Naidoo is a senior director in Industry Strategy and Insight at Oracle. 

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  • Delivering the Integrated Portal Experience!

    - by Michael Snow
    v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Guest post by Richard Maldonado, Principal Product Manager, Oracle WebCenter Portal Organizations are still struggling to standardize on a user interaction platform which can meet the needs of all their target audiences.  This has not only resulted in inefficient and inconsistent experiences for their users, but it also creates inefficiencies (productivity and costs) for the departments that manage the applications and information systems.  Portals have historically been the unifying platform that provide IT with a common interface which can securely surface the most relevant interactions for a given user and/or group of users.  However, organizations have found that the technologies available have either not provided the flexibility necessary to address all of their use cases, or they rely too much on IT resources to manage, maintain, and evolve.  Empowering  the Business Groups The core issue that IT departments face with delivering portal experiences is having enough resources to respond and address the influx of requirements which come in from the business.  Commonly, when a business group wants a new portal site established for their group, they will submit a request to the IT dept, the IT dept then assigns a resource to an administrator and/or developer to build.  Unfortunately, this approach is not scalable, it can be a time consuming activity which requires significant interaction between the business owner and the IT resource.  A modern user interaction platforms should empower the business groups by providing them tools which they can use to build and manage the portal experiences without the need for IT's involvement.  And because business groups rarely have technical resources (developers) on staff, the tools must be easy enough that virtually any business user could use.  In addition, the tool must be powerful enough to allow them to build the experience that they need, things such as creating a whole new portal, add/manage page and page hierarchy, manage user/group access, add/modify components within the page, etc.  This balance between ease-of-use and flexibility is key to the successful adoption of tools which will ultimately reduce the burden on IT, respond to the needs of the business, and deliver high-value experiences for the users.  Ready or Not, Here They Come: Smartphones and Tablets Recently, several studies have highlighted that smartphone and tablet-style devices have overtaken PC's in both sales and usage.  This shift is further driving organizations to revaluate how they're delivering data, information, and applications to their users.  Users are expecting to get the same level of access and interaction, but in a ways which are optimized for the capabilities of the device that they are using.  Expect More With the ever growing number of new IT projects and flat/shrinking budgets, organizations are looking for comprehensive solutions which can deliver integrated web experiences that are tailored for the users and optimized for mobile devices.  Piecing together a number of point solutions is no longer an option.  A modern portal technology should not only address the traditional needs of integrating and surfacing back-end applications/information, but it should enable the business through easy-to-use tools and accelerate the delivery of mobile optimized experiences.   v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} 12.00 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} 12.00 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-family:"Calibri","sans-serif"; mso-ascii- mso-ascii-theme-font:minor-latin; mso-hansi- mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} WebCenter in Action Series: Qualcomm Provides a Seamless Experience for Customers with Oracle WebCenter Featuring Qualcomm & Keste 12.00 Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 -"/ /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} 12.00 Normal 0 false false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-family:"Calibri","sans-serif"; mso-fareast- mso-bidi-font-family:"Times New Roman";}

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  • Combined SOAP/JSON/XML in WCF, using UriTemplate

    - by gregmac
    I'm trying to build a generic web service interface using WCF, to allow 3rd party developers to hook into our software. After much struggling and reading (this question helped a lot), I finally got SOAP, JSON and XML (POX) working together. To simplify, here's my code (to make this example simple, I'm not using interfaces -- I did try this both ways): <ServiceContract()> _ Public Class TestService Public Sub New() End Sub <OperationContract()> _ <WebGet()> _ Public Function GetDate() As DateTime Return Now End Function '<WebGet(UriTemplate:="getdateoffset/{numDays}")> _ <OperationContract()> _ Public Function GetDateOffset(ByVal numDays As Integer) As DateTime Return Now.AddDays(numDays) End Function End Class and the web.config code: <services> <service name="TestService" behaviorConfiguration="TestServiceBehavior"> <endpoint address="soap" binding="basicHttpBinding" contract="TestService"/> <endpoint address="json" binding="webHttpBinding" behaviorConfiguration="jsonBehavior" contract="TestService"/> <endpoint address="xml" binding="webHttpBinding" behaviorConfiguration="poxBehavior" contract="TestService"/> <endpoint address="mex" contract="IMetadataExchange" binding="mexHttpBinding" /> </service> </services> <behaviors> <endpointBehaviors> <behavior name="jsonBehavior"> <enableWebScript/> </behavior> <behavior name="poxBehavior"> <webHttp /> </behavior> </endpointBehaviors> <serviceBehaviors> <behavior name="TestServiceBehavior"> <serviceMetadata httpGetEnabled="true"/> <serviceDebug includeExceptionDetailInFaults="false"/> </behavior> </serviceBehaviors> </behaviors> This actually works -- I'm able to go to TestService.svc/xml/GetDate for xml, TestService.svc/json/GetDate for json, and point a SOAP client at TestService.svc?wsdl and have the SOAP queries work. The part I'd like to fix is the queries. I have to use TestService.svc/xml/GetDateOffset?numDays=4 instead of TestService.svc/xml/GetDateOffset/4. If I specify the UriTemplate, I get the error: Endpoints using 'UriTemplate' cannot be used with 'System.ServiceModel.Description.WebScriptEnablingBehavior'. But of course without using <enableWebScript/>, JSON doesn't work. The only other thing I've seen that I think will work is making 3 different services (.svc files), that all implement an interface that specifies the contract, but in the classes specify different WebGet/WebInvoke attributes on each class. This seems like a lot of extra work, that frankly, I don't see why the framework doesn't handle for me. The implementation of the classes would all be the same, except for the attributes, which means over time it would be easy for bugs/changes to get fixed/done in one implementation but not the others, leading to inconsistent behaviour when using the JSON vs SOAP implementation for example. Am I doing something wrong here? Am I taking a totally wrong approach and misusing WCF? Is there a better way to do this? With my experience doing web stuff, I think it should be possible for some kind of framework to handle this ... I even have an idea in my head of how to build it. It just seems like WCF is supposed to be doing this, and I don't really want to reinvent the wheel.

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  • issue with std::advance on std::sets

    - by tim
    I've stumbled upon what I believe is a bug in the stl algorithm advance. When I'm advancing the iterator off of the end of the container, I get inconsistent results. Sometimes I get container.end(), sometimes I get the last element. I've illustrated this with the following code: #include <algorithm> #include <cstdio> #include <set> using namespace std; typedef set<int> tMap; int main(int argc, char** argv) { tMap::iterator i; tMap the_map; for (int i=0; i<10; i++) the_map.insert(i); #if EXPERIMENT==1 i = the_map.begin(); #elif EXPERIMENT==2 i = the_map.find(4); #elif EXPERIMENT==3 i = the_map.find(5); #elif EXPERIMENT==4 i = the_map.find(6); #elif EXPERIMENT==5 i = the_map.find(9); #elif EXPERIMENT==6 i = the_map.find(2000); #else i = the_map.end(); #endif advance(i, 100); if (i == the_map.end()) printf("the end\n"); else printf("wuh? %d\n", *i); return 0; } Which I get the following unexpected (according to me) behavior in experiment 3 and 5 where I get the last element instead of the_map.end(). [tim@saturn advance]$ uname -srvmpio Linux 2.6.18-1.2798.fc6 #1 SMP Mon Oct 16 14:37:32 EDT 2006 i686 athlon i386 GNU/Linux [tim@saturn advance]$ g++ --version g++ (GCC) 4.1.1 20061011 (Red Hat 4.1.1-30) Copyright (C) 2006 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. [tim@saturn advance]$ g++ -DEXPERIMENT=1 advance.cc [tim@saturn advance]$ ./a.out the end [tim@saturn advance]$ g++ -DEXPERIMENT=2 advance.cc [tim@saturn advance]$ ./a.out the end [tim@saturn advance]$ g++ -DEXPERIMENT=3 advance.cc [tim@saturn advance]$ ./a.out wuh? 9 [tim@saturn advance]$ g++ -DEXPERIMENT=4 advance.cc [tim@saturn advance]$ ./a.out the end [tim@saturn advance]$ g++ -DEXPERIMENT=5 advance.cc [tim@saturn advance]$ ./a.out wuh? 9 [tim@saturn advance]$ g++ -DEXPERIMENT=6 advance.cc [tim@saturn advance]$ ./a.out the end [tim@saturn advance]$ g++ -DEXPERIMENT=7 advance.cc [tim@saturn advance]$ ./a.out the end [tim@saturn advance]$ From the sgi website (see link at top), it has the following example: list<int> L; L.push_back(0); L.push_back(1); list<int>::iterator i = L.begin(); advance(i, 2); assert(i == L.end()); I would think that the assertion should apply to other container types, no? What am I missing? Thanks!

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  • StaleDataException: access closed cursor

    - by Aurora
    In my application, after enough clicking around, I get this error: 06-08 19:47:59.967: ERROR/AndroidRuntime(2429): java.lang.RuntimeException: Unable to pause activity {com.MYAPP.app/com.MYAPP.app.MainActivity}: android.database.StaleDataException: Access closed cursor What I have is a Tab Activity (my MainActivity), which has a ListActivity as the contents for each tab. Inside the onCreate for each ListActivity I get a cursor that represents the data to be displayed in that list. The onListItemClick for each list also creates another activity, so clicking on an item in the list will show more information about that item in a new screen. It's inconsistent, but after enough clicking into these new activities, or going back to the ListView from a new activity, the program crashes. In searching around for a solution to my problem, I did stumble upon registerDataSetObserver, but it doesn't seem to be the whole answer. I am also having trouble finding documentation on it, so I'm not sure I fully understand it. I have a custom ListAdapter that both my ListViews use and have called registerDataSetObservers on the cursors there. I have attached the relevant code from one of my ListActivities and from my custom ListAdapter class. The ListActivity. I have two of these, almost identical, except they both have different cursors created from different database queries: import com.MYAPP.app.listmanager.DeviceListAdapter; public class AllSensorsActivity extends ListActivity{ private DeviceListAdapter AllList; private DbManager db; protected Cursor AllCur; protected Cursor AllSensors; private static final String TAG = "AllSensorsActivity"; @Override public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); Log.e(TAG, "Calling All onCreate"); db = new DbManager(this); db.open(); AllCur = db.fetchAllDevices(); startManagingCursor(AllCur); AllSensors = db.fetchAllSensors(); startManagingCursor(AllSensors); AllList = new DeviceListAdapter(this, AllCur, AllSensors); setListAdapter(AllList); } @Override protected void onListItemClick(ListView l, View v, int position, long id){ String device_name = (String) ((DeviceListAdapter)getListAdapter()).getItem(position); String sensor_string = ((DeviceListAdapter)getListAdapter()).getSensors(id); Intent i = new Intent(this, SensorActivity.class); Bundle bundle = new Bundle(); bundle.putString("NAME", device_name); i.putExtras(bundle); bundle.putString("SENSORS", sensor_string); i.putExtras(bundle); this.startActivity(i); } The custom ListAdapter: public class DeviceListAdapter extends BaseAdapter { private static final String TAG = "DeviceListAdapter"; private Context mContext; private Cursor mSensors; private Cursor mDevices; protected MyDataSetObserver sensors_observer; protected MyDataSetObserver devices_observer; public DeviceListAdapter(Context context, Cursor devices, Cursor sensors){ mContext = context; mDevices = devices; mSensors = sensors; sensors_observer = new MyDataSetObserver(); mSensors.registerDataSetObserver(sensors_observer); devices_observer = new MyDataSetObserver(); mDevices.registerDataSetObserver(devices_observer); } // ... more functions and stuff that are not relevant go down here... } private class MyDataSetObserver extends DataSetObserver { public void onChanged(){ Log.e(TAG, "CHANGED CURSOR!"); } public void onInvalidated(){ Log.e(TAG, "INVALIDATED CURSOR!"); } } Should I just have MyDataSetObserver catch the exception and move on? I'd like a more robust solution than that if possible. Or is there some other way I could rearrange my program so that the staleDataException doesn't occur (as often)? I believe that it is happening because I am launching the new activity in my onListItemClick.

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  • PROJECT HELP NEEDED. SOME BASIC CONCEPTS GREAT CONFUSION BECAUSE OF LACK OF PROPER MATERIAL PLEASE H

    - by user287745
    Task ATTENDENCE RECORDER AND MANAGEMENT SYSTEM IN DISTRIBUTED ENVIRONMENT ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Example implementation needed. a main server in each lab where the operator punches in the attendence of the student. =========================================================== scenerio:- a college, 10 departments, all departments have a computer lab with 60-100 computers, the computers within each lab are interconnected and all computers in any department have to dail to a particular number (THE NUMBER GIVEN BY THE COLLEGE INTERNET DEPARTMENT) to get connected to the internet. therefore safe to assume that there is a central location to which all the computers in the college are connected to. there is a 'students attendence portal' which can be accessed using internet explorer, students enter there id and get the particular attendence record regarding to the labs only. a description of the working is like:- 1) the user will select which department, which year has arrived to the lab 2) the selection will give the user a return of all the students name and there roll numbers belonging to that department; 'with a check box to "TICK MARK IF THE STUDENT IS PRESENT" ' 3) A SUBMIT BUTTON when pressed reads the 'id' of the checkbox to determine the "particular count number of the student" from that an id of the student is constructed and that id is inserted with a present. (there is also date and time and much more to normalize the db and to avoid conflicts and keep historic records etc but that you will have to assume) steps taken till this date:- ( please note we are not computer students, we are to select something of some other line as a project!, as you will read in my many post 'i" have designed small websites just out of liking. have never ever done any thing official to implement like this.) * have made the database fully normalized. * have made the website which does the functions required on the database. Testing :- deployed the db and site on a free aspspider server and it worked. tested from several computers. Now the problem please help thank youuuuuuuu a practical demonstration has to be done within the college network. no internet! we have been assigned a lab - 60 computers- to demonstrate. (please dont give replies as 60 computers only! is not a big deal one CPU can manage it. i know that; IT IS A HYPOTHETICAL SITUATION WHERE WE ASSUME THAT 60 IS NOT 60 BUT ITS LIKE 60,000 COMPUTERS) 1a) make a web server, yes iis and put files in www folder and configure server to run aspx files- although a link to a step by step guide will be appreciated)\ ? which version of windows should i ask for xp or win server 2000 something? 2a) make a database server. ( well yes install sql server 2005, okay but then what? just put the database file on a pc share it and append the connection string to the share? ) 3a) make the site accessible from the remaining computers ? http://localhost/sitename ? all users "being operators of the particular lab" have the right to edit, write or delete(in dispute), thereby any "users" who hate our program can make the database inconsistent by accessing te same record and doing different edits and then complaining? so how to prevent this? you know something like when the db table is being written to others can only read but not write.. one big confusion:- IN DISTRIBUTED ENVIRONMENT "how to implement this" where does "distributed environment" come in! meaning :- alright the labs are in different departments but the "database server will be one" the "web server will be one" so whats distributed!?

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  • Trouble with Code First DatabaseGenerated Composite Primary Key

    - by Nick Fleetwood
    This is a tad complicated, and please, I know all the arguments against natural PK's, so we don't need to have that discussion. using VS2012/MVC4/C#/CodeFirst So, the PK is based on the date and a corresponding digit together. So, a few rows created today would be like this: 20131019 1 20131019 2 And one created tomorrow: 20131020 1 This has to be automatically generated using C# or as a trigger or whatever. The user wouldn't input this. I did come up with a solution, but I'm having problems with it, and I'm a little stuck, hence the question. So, I have a model: public class MainOne { //[Key] //public int ID { get; set; } [Key][Column(Order=1)] [DatabaseGenerated(DatabaseGeneratedOption.None)] public string DocketDate { get; set; } [Key][Column(Order=2)] [DatabaseGenerated(DatabaseGeneratedOption.None)] public string DocketNumber { get; set; } [StringLength(3, ErrorMessage = "Corp Code must be three letters")] public string CorpCode { get; set; } [StringLength(4, ErrorMessage = "Corp Code must be four letters")] public string DocketStatus { get; set; } } After I finish the model, I create a new controller and views using VS2012 scaffolding. Then, what I'm doing is debugging to create the database, then adding the following instead of trigger after Code First creates the DB [I don't know if this is correct procedure]: CREATE TRIGGER AutoIncrement_Trigger ON [dbo].[MainOnes] instead OF INSERT AS BEGIN DECLARE @number INT SELECT @number=COUNT(*) FROM [dbo].[MainOnes] WHERE [DocketDate] = CONVERT(DATE, GETDATE()) INSERT INTO [dbo].[MainOnes] (DocketDate,DocketNumber,CorpCode,DocketStatus) SELECT (CONVERT(DATE, GETDATE ())),(@number+1),inserted.CorpCode,inserted.DocketStatus FROM inserted END And when I try to create a record, this is the error I'm getting: The changes to the database were committed successfully, but an error occurred while updating the object context. The ObjectContext might be in an inconsistent state. Inner exception message: The object state cannot be changed. This exception may result from one or more of the primary key properties being set to null. Non-Added objects cannot have null primary key values. See inner exception for details. Now, what's interesting to me, is that after I stop debugging and I start again, everything is perfect. The trigger fired perfectly, so the composite PK is unique and perfect, and the data in other columns is intact. My guess is that EF is confused by the fact that there is seemingly no value for the PK until AFTER an insert command is given. Also, appearing to back this theory, is that when I try to edit on of the rows, in debug, I get the following error: The number of primary key values passed must match number of primary key values defined on the entity. Same error occurs if I try to pull the 'Details' or 'Delete' function. Any solution or ideas on how to pull this off? I'm pretty open to anything, even creating a hidden int PK. But it would seem redundant. EDIT 21OCT13 [HttpPost] public ActionResult Create(MainOne mainone) { if (ModelState.IsValid) { var countId = db.MainOnes.Count(d => d.DocketDate == mainone.DocketNumber); //assuming that the date field already has a value mainone.DocketNumber = countId + 1; //Cannot implicitly convert type int to string db.MainOnes.Add(mainone); db.SaveChanges(); return RedirectToAction("Index"); } return View(mainone); } EDIT 21OCT2013 FINAL CODE SOLUTION For anyone like me, who is constantly searching for clear and complete solutions. if (ModelState.IsValid) { String udate = DateTime.UtcNow.ToString("yyyy-MM-dd"); mainone.DocketDate = udate; var ddate = db.MainOnes.Count(d => d.DocketDate == mainone.DocketDate); //assuming that the date field already has a value mainone.DocketNumber = ddate + 1; db.MainOnes.Add(mainone); db.SaveChanges(); return RedirectToAction("Index"); }

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  • compareTo() method java is acting weird

    - by Ron Paul
    hi im having trouble getting this to work im getting an error here with my object comparison...how could I cast the inches to a string ( i never used compare to with anything other than strings) , or use comparison operators to compare the intigers, Object comparison = this.inches.compareTo(obj.inches); here is my code so far import java.io.*; import java.util.*; import java.lang.Integer; import java.lang.reflect.Array; public class Distance implements Comparable<Distance> { private static final String HashCodeUtil = null; private int feet; private int inches; private final int DEFAULT_FT = 1; private final int DEFAULT_IN = 1; public Distance(){ feet = DEFAULT_FT; inches = DEFAULT_IN; } public Distance(int ft, int in){ feet = ft; inches = in; } public void setFeet(int ft){ try { if(ft<0){ throw new CustomException("Distance is not negative"); } } catch(CustomException c){ System.err.println(c); feet =ft; } } public int getFeet(){ return feet; } public void setInches(int in){ try { if (in<0) throw new CustomException("Distance is not negative"); //inches = in; } catch(CustomException c) { System.err.println(c); inches = in; } } public int getInches(){ return inches; } public String toString (){ return "<" + feet + ":" + inches + ">"; } public Distance add(Distance m){ Distance n = new Distance(); n.inches = this.inches + m.inches; n.feet = this.feet + m.feet; while(n.inches>12){ n.inches = n.inches - 12; n.feet++; } return n; } public Distance subtract(Distance f){ Distance m = new Distance(); m.inches = this.inches - f.inches; m.feet = this.feet - f.feet; while(m.inches<0){ m.inches = m.inches - 12; feet--; } return m; } @Override public int compareTo(Distance obj) { // TODO Auto-generated method stub final int BEFORE = -1; final int EQUAL = 0; final int AFTER = 1; if (this == obj) return EQUAL; if(this.DEFAULT_IN < obj.DEFAULT_FT) return BEFORE; if(this.DEFAULT_IN > obj.DEFAULT_FT) return AFTER; Object comparison = this.inches.compareTo(obj.inches); if (this.inches == obj.inches) return compareTo(null); assert this.equals(obj) : "compareTo inconsistent with equals"; return EQUAL; } @Override public boolean equals( Object obj){ if (obj != null) return false; if (!(obj intanceof Distance)) return false; Distance that = (Distance)obj; ( this.feet == that.feet && this.inches == that.inches); return true; else return false; } @Override public int hashCode(int, int) { int result = HashCodeUtil.inches; result = HashCodeUtil.hash(result, inches ); result = HashCodeUtil.hash(result, feet); ruturn result; }

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  • SQL SERVER – Concurrency Basics – Guest Post by Vinod Kumar

    - by pinaldave
    This guest post is by Vinod Kumar. Vinod Kumar has worked with SQL Server extensively since joining the industry over a decade ago. Working on various versions from SQL Server 7.0, Oracle 7.3 and other database technologies – he now works with the Microsoft Technology Center (MTC) as a Technology Architect. Let us read the blog post in Vinod’s own voice. Learning is always fun when it comes to SQL Server and learning the basics again can be more fun. I did write about Transaction Logs and recovery over my blogs and the concept of simplifying the basics is a challenge. In the real world we always see checks and queues for a process – say railway reservation, banks, customer supports etc there is a process of line and queue to facilitate everyone. Shorter the queue higher is the efficiency of system (a.k.a higher is the concurrency). Every database does implement this using checks like locking, blocking mechanisms and they implement the standards in a way to facilitate higher concurrency. In this post, let us talk about the topic of Concurrency and what are the various aspects that one needs to know about concurrency inside SQL Server. Let us learn the concepts as one-liners: Concurrency can be defined as the ability of multiple processes to access or change shared data at the same time. The greater the number of concurrent user processes that can be active without interfering with each other, the greater the concurrency of the database system. Concurrency is reduced when a process that is changing data prevents other processes from reading that data or when a process that is reading data prevents other processes from changing that data. Concurrency is also affected when multiple processes are attempting to change the same data simultaneously. Two approaches to managing concurrent data access: Optimistic Concurrency Model Pessimistic Concurrency Model Concurrency Models Pessimistic Concurrency Default behavior: acquire locks to block access to data that another process is using. Assumes that enough data modification operations are in the system that any given read operation is likely affected by a data modification made by another user (assumes conflicts will occur). Avoids conflicts by acquiring a lock on data being read so no other processes can modify that data. Also acquires locks on data being modified so no other processes can access the data for either reading or modifying. Readers block writer, writers block readers and writers. Optimistic Concurrency Assumes that there are sufficiently few conflicting data modification operations in the system that any single transaction is unlikely to modify data that another transaction is modifying. Default behavior of optimistic concurrency is to use row versioning to allow data readers to see the state of the data before the modification occurs. Older versions of the data are saved so a process reading data can see the data as it was when the process started reading and not affected by any changes being made to that data. Processes modifying the data is unaffected by processes reading the data because the reader is accessing a saved version of the data rows. Readers do not block writers and writers do not block readers, but, writers can and will block writers. Transaction Processing A transaction is the basic unit of work in SQL Server. Transaction consists of SQL commands that read and update the database but the update is not considered final until a COMMIT command is issued (at least for an explicit transaction: marked with a BEGIN TRAN and the end is marked by a COMMIT TRAN or ROLLBACK TRAN). Transactions must exhibit all the ACID properties of a transaction. ACID Properties Transaction processing must guarantee the consistency and recoverability of SQL Server databases. Ensures all transactions are performed as a single unit of work regardless of hardware or system failure. A – Atomicity C – Consistency I – Isolation D- Durability Atomicity: Each transaction is treated as all or nothing – it either commits or aborts. Consistency: ensures that a transaction won’t allow the system to arrive at an incorrect logical state – the data must always be logically correct.  Consistency is honored even in the event of a system failure. Isolation: separates concurrent transactions from the updates of other incomplete transactions. SQL Server accomplishes isolation among transactions by locking data or creating row versions. Durability: After a transaction commits, the durability property ensures that the effects of the transaction persist even if a system failure occurs. If a system failure occurs while a transaction is in progress, the transaction is completely undone, leaving no partial effects on data. Transaction Dependencies In addition to supporting all four ACID properties, a transaction might exhibit few other behaviors (known as dependency problems or consistency problems). Lost Updates: Occur when two processes read the same data and both manipulate the data, changing its value and then both try to update the original data to the new value. The second process might overwrite the first update completely. Dirty Reads: Occurs when a process reads uncommitted data. If one process has changed data but not yet committed the change, another process reading the data will read it in an inconsistent state. Non-repeatable Reads: A read is non-repeatable if a process might get different values when reading the same data in two reads within the same transaction. This can happen when another process changes the data in between the reads that the first process is doing. Phantoms: Occurs when membership in a set changes. It occurs if two SELECT operations using the same predicate in the same transaction return a different number of rows. Isolation Levels SQL Server supports 5 isolation levels that control the behavior of read operations. Read Uncommitted All behaviors except for lost updates are possible. Implemented by allowing the read operations to not take any locks, and because of this, it won’t be blocked by conflicting locks acquired by other processes. The process can read data that another process has modified but not yet committed. When using the read uncommitted isolation level and scanning an entire table, SQL Server can decide to do an allocation order scan (in page-number order) instead of a logical order scan (following page pointers). If another process doing concurrent operations changes data and move rows to a new location in the table, the allocation order scan can end up reading the same row twice. Also can happen if you have read a row before it is updated and then an update moves the row to a higher page number than your scan encounters later. Performing an allocation order scan under Read Uncommitted can cause you to miss a row completely – can happen when a row on a high page number that hasn’t been read yet is updated and moved to a lower page number that has already been read. Read Committed Two varieties of read committed isolation: optimistic and pessimistic (default). Ensures that a read never reads data that another application hasn’t committed. If another transaction is updating data and has exclusive locks on data, your transaction will have to wait for the locks to be released. Your transaction must put share locks on data that are visited, which means that data might be unavailable for others to use. A share lock doesn’t prevent others from reading but prevents them from updating. Read committed (snapshot) ensures that an operation never reads uncommitted data, but not by forcing other processes to wait. SQL Server generates a version of the changed row with its previous committed values. Data being changed is still locked but other processes can see the previous versions of the data as it was before the update operation began. Repeatable Read This is a Pessimistic isolation level. Ensures that if a transaction revisits data or a query is reissued the data doesn’t change. That is, issuing the same query twice within a transaction cannot pickup any changes to data values made by another user’s transaction because no changes can be made by other transactions. However, this does allow phantom rows to appear. Preventing non-repeatable read is a desirable safeguard but cost is that all shared locks in a transaction must be held until the completion of the transaction. Snapshot Snapshot Isolation (SI) is an optimistic isolation level. Allows for processes to read older versions of committed data if the current version is locked. Difference between snapshot and read committed has to do with how old the older versions have to be. It’s possible to have two transactions executing simultaneously that give us a result that is not possible in any serial execution. Serializable This is the strongest of the pessimistic isolation level. Adds to repeatable read isolation level by ensuring that if a query is reissued rows were not added in the interim, i.e, phantoms do not appear. Preventing phantoms is another desirable safeguard, but cost of this extra safeguard is similar to that of repeatable read – all shared locks in a transaction must be held until the transaction completes. In addition serializable isolation level requires that you lock data that has been read but also data that doesn’t exist. Ex: if a SELECT returned no rows, you want it to return no. rows when the query is reissued. This is implemented in SQL Server by a special kind of lock called the key-range lock. Key-range locks require that there be an index on the column that defines the range of values. If there is no index on the column, serializable isolation requires a table lock. Gets its name from the fact that running multiple serializable transactions at the same time is equivalent of running them one at a time. Now that we understand the basics of what concurrency is, the subsequent blog posts will try to bring out the basics around locking, blocking, deadlocks because they are the fundamental blocks that make concurrency possible. Now if you are with me – let us continue learning for SQL Server Locking Basics. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Concurrency

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